BERLIN
— It's been two years since Lance Armstrong retired from professional cycling. But instead of watching new stars rise, the sport's fans have had little to cheer lately.

Riders in the Tour de France crossed the finish line on the Champs d'Elysées in Paris Sunday under one of the darkest clouds in the event's 104-year history. Spain's Alberto Contador won. But during the three-week race, three riders tested positive for banned substances, and Denmark's Michael Rasmussen, the race leader, was kicked off his team Wednesday amid doping suspicions. Two teams pulled out of the Tour last week after their riders were implicated in doping violations.

Some cycling observers say the sport is finally cleaning up its act, and this year will mark a turning point. Others say the clouds won't dissipate soon.

Some TV networks have stopped broadcasting the sport. Across Europe, corporate sponsors are pulling their support or at least reconsidering their backing of cycling teams. Germany's Interior Ministry might cancel the World Cycling Championships scheduled for September in Stuttgart. Even cycling's place in the Olympics is set for debate.

But amid the scandals is what some call a last-ditch effort to save the sport: European countries are passing antidoping laws. Funding for drug testing is set to increase. Cycling teams are pledging to make testing integral to their programs.

Pat McQuaid, the embattled president of the International Cycling Union, the sport's governing body, says cycling has reached "a turning point" and that a major revolution is already under way.

Mr. McQuaid says the 400 drug tests that took place at this year's Tour, the most ever, worked – and three positive tests is proof of that. "Out of 190 guys, that's not a lot," he says. "There are 187 guys in there that were riding clean, and haven't [tested positive]."

A year of scandals to overcome

But given the past year, it is hard for some to share McQuaid's optimism.

Just before the 2006 Tour de France, Spanish police busted a doctor who was allegedly a part of a massive doping ring. His files implicated hundreds of top athletes, including dozens of cyclists.

Days after last year's Tour ended, the winner, American Floyd Landis, tested positive for banned testosterone; his case is still under appeal.

This spring, some of the sport's biggest names admitted to using erythropoietin, or EPO, in the 1990s. EPO, a cancer drug, helps athletes' endurance by boosting the number of oxygen-carrying red blood cells in the body.

No country was rocked harder than Germany, which has had a love affair with cycling ever since 23-year-old Jan Ullrich won the Tour de France in 1997 while riding for the German Telekom team, now called T-Mobile.

After Spanish authorities found nine bags of his blood in the 2006 "Operation Puerto" doping bust, T-Mobile fired Ullrich. Several of his former T-Mobile teammates came forward this spring to admit using EPO in the 1990s, while Ullrich maintains his innocence.

The confessions were portrayed as a sign that cycling was on the mend. But some longtime observers didn't buy it.

"In my opinion it was mostly a confession for show. They told us some small parts of the doping reality," says Ralf Meutgens, a former German national coach and author of the book "Doping im Radsport" (Doping in Cycling), published this April. "The whole truth would be truly shocking for the public."

The scandals are hitting the sport where it hurts most – the wallet.

When the first doping scandal surfaced at this year's Tour de France, Germany's two public television networks, ARD and ZDF, pulled the plug on live coverage of the event. ZDF, which had been broadcasting the Tour since 1998, says the decision cost it as much as 400,000 euros ($545,880) in lost advertising.

Two-thirds of the station's viewers supported the move, ZDF editor in chief Nikolaus Brender says. "Our viewers have made it very clear: They are interested in the Tour de France, but in a Tour de France as a sports event. They are not interested in an event that is a pharmaceutical show."

More than most sports, cycling is dependent on sponsors. The sport doesn't generate revenue from ticket sales. Instead, almost a million people turn out to watch the Tour from curbside seats as it rolls through France, while millions more tune in on television.

But overall, cycling's viewership has taken a hit in the past year. IFM, a German market-research firm, calculated that the publicity value of sponsorships dropped 52 percent after the tainted 2006 Tour.

The seemingly nonstop scandals since have even longtime cycling sponsors like T-Mobile, Deutsche Bank, Credit Agricole, and Czech carmaker Skoda reconsidering their support for the sport.

"Now it's a very bad time for cycling and for sport in general," says T-Mobile spokesman Christian Frommert. "We are a big company in Germany, and we have to raise our voice about some of these things."

Mr. Frommert says the company is struggling to decide whether to end its cycling sponsorship after 16 years.

The doping scandals have brought a political reaction as well. German Interior Minister Wolfgang Schaeuble is calling the Stuttgart championships, scheduled for Sept. 25-30, the last chance for cycling.

But Mr. Schaeuble is also threatening to pull government funding for the event – 150,000 euros – and perhaps ban it altogether if it can't be certifiably free of cheating.

Some are saying the sport needed to hit bottom before it could really clean itself up. In the last month, Austria and Germany passed strict antidoping laws that make using banned performance-enhancers a federal crime.

It will still be up to individual sports associations to enforce sanctions, but the new laws require athletes to cooperate with authorities in determining the source of the illegal substances used.

"It's necessary to have this law to find out who's standing behind the athletes, to find out the criminal networks," says Ulrike Spitz, who works at the German Anti-Doping Agency, or NADA.

The German government has pledged to nearly quadruple NADA's funding, to 4 million euros a year. The Interior Ministry is also pledging to increase the public funds used for German sports next year, from 105 million euros to 120 million euros – though the opposition Social Democrats object.

"We have to make sure to keep all the good qualities of sport for our society and that can only happen by putting more money into the system and enhancing the fight against doping," Mr. Sachs says.

German cycling sponsors are diverting money from their budgets to strengthen NADA. T-Mobile has already given NADA 200,000 euros to date and has pledged to give another 250,000 euros by the end of the year. Another company, Nordmilch, which sponsors Team Milram, just pledged 150,000 euros in funding.

Perhaps most important, the teams themselves are beginning to take responsibility for riders' behavior. On teams like T-Mobile and CSC, riders are tested internally all season long.

Many say the coming months will be critical. "The sport of cycling seems to be able to damage itself but unable to help itself," says Meutgens, the author. "Let's hope the next year will be different."

A history of scandals and cheating

Allegations of doping have plagued the Tour de France since the early 1900s, when riders drank alcohol and used substances to dull pain. In the past 50 years, some riders have used amphetamines to increase stamina and ignore pain, anabolic steroids to gain muscle and strength, or erythropoietin (EPO) to stimulate red-blood-cell production and improve oxygen-carrying capacity.

Since the race's inception in 1903, allegations of doping have pursued cycling's premier race:

2007: Alexandre Vinokourov, from Kazakhstan, is forced out of this year's Tour, along with all members of the Astana team, after he tests positive for a banned blood transfusion.

2007: Bjarne Riis confesses to using EPO during his 1996 Tour win. Now head of Team CSC, he decides not to join the team for the start of the race in London on July 7.

2006: Jan Ullrich is forced out on the eve of the Tour after being linked to a massive Spanish investigation into a blood-doping scandal that implicates more than 50 riders. The 1997 Tour winner denies any wrongdoing.

2006: Italian rider Ivan Basso is also kicked out of the Tour. He receives a two-year doping penalty from his cycling federation.

2006: Tour de France winner Floyd Landis' team says he tested positive for high levels of testosterone after his Stage 17 win. The American hopes to overturn the US Anti-Doping Agency's decision and prove he did not take testosterone. Landis says the French lab made key errors.

2005: Spaniard Roberto Heras is banned for two years for testing positive for EPO in the Tour of Spain, which he won.

2004: Codifis team rider Philippe Gaumont tells investigators doping was widespread in the team; French police detain British cyclist David Millar (EPO syringes were found in his apartment).